INTRODUCTION TO
COMSOL Multiphysics
I n t r o d u c t i o n t o C O M S O L M u l t i p h y s i c s
© 1998–2017 COMSOL
Protected by patents listed on www.comsol.com/patents, and U.S. Patents 7,519,518; 7,596,474; 7,623,991; 8,457,932;
8,954,302; 9,098,106; 9,146,652; 9,323,503; 9,372,673; and 9,454,625. Patents pending.
This Documentation and the Programs described herein are furnished under the COMSOL Software License
Agreement (www.comsol.com/comsol-license-agreement) and may be used or copied only under the terms of the
license agreement.
COMSOL, the COMSOL logo, COMSOL Multiphysics, COMSOL Desktop, COMSOL Server, and LiveLink are either
registered trademarks or trademarks of COMSOL AB. All other trademarks are the property of their respective
owners, and COMSOL AB and its subsidiaries and products are not affiliated with, endorsed by, sponsored by, or
supported by those trademark owners. For a list of such trademark owners, see www.comsol.com/trademarks.
Version: COMSOL 5.3a
C o n t a c t I n f o r m a t i o n
Visit the Contact COMSOL page at www.comsol.com/contact to submit general inquiries,
contact Technical Support, or search for an address and phone number. You can also visit the
Worldwide Sales Offices page at www.comsol.com/contact/offices for address and contact
information.
If you need to contact Support, an online request form is located at the COMSOL Access page at
www.comsol.com/support/case. Other useful links include:
• Support Center: www.comsol.com/support
Product Download: www.comsol.com/product-download
Product Updates: www.comsol.com/support/updates
COMSOL Blog: www.comsol.com/blogs
Discussion Forum: www.comsol.com/community
Events: www.comsol.com/events
COMSOL Video Gallery: www.comsol.com/video
Support Knowledge Base: www.comsol.com/support/knowledgebase
Part number: CM010004
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
COMSOL Desktop® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Example 1: Structural Analysis of a Wrench. . . . . . . . . . . . . . . 31
Model Wizard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Global Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Physics and Boundary Conditions . . . . . . . . . . . . . . . . . . . . . 39
Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Convergence Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Example 2: The Busbar — A Multiphysics Model . . . . . . . . . . 54
Model Wizard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Global Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Auto Completion and Find for Parameters and Variables . 60
Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Physics and Boundary Conditions . . . . . . . . . . . . . . . . . . . . . 70
Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
| 3
Building an Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Advanced Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Parameters, Functions, Variables, and Couplings . . . . . . . . . 98
Material Properties and Material Libraries. . . . . . . . . . . . . . 102
Adding Meshes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Adding Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Parametric Sweeps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Parallel Computing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
COMSOL Multiphysics Client-Server . . . . . . . . . . . . . . . . . 143
Appendix A — Building a Geometry . . . . . . . . . . . . . . . . . . . 146
Appendix B — Keyboard and Mouse Shortcuts . . . . . . . . . . 162
Appendix C — Language Elements and Reserved Names . 166
Appendix D — File Formats . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Appendix E — Connecting with LiveLink™ Add-Ons . . . . . 187
4 |
Introduction
Read this book if you are new to COMSOL Multiphysics®. It provides an
overview of the COMSOL® environment with examples that show you how to use
the COMSOL Desktop® user interface and the Model Builder. It also provides a
quick introduction to creating applications using the Application Builder.
If you have not yet installed the software, install it now according to the
instructions at www.comsol.com/product-download.
In addition to this book, an extensive documentation set is available after
installation. Tutorials can be found throughout the COMSOL website, including
in the Video Gallery at www.comsol.com/videos and on the COMSOL Blog at
www.comsol.com/blogs.
| 5
COMSOL Desktop®
QUICK ACCESS TOOLBAR — Use these
buttons for access to functionality such as file
open/save, undo/redo, copy/paste, and delete.
RIBBON — The ribbon tabs have buttons
and drop-down lists for controlling all
steps of the modeling process.
APPLICATION BUILDER —
Click this button to switch to
the Application Builder and
start building an application
MODEL BUILDER
TOOLBAR
MODEL TREE — The model tree
gives an overview of the model and all
of the functionality and operations
needed for building and solving a
model as well as processing the results.
6 |
MODEL BUILDER — The
Model Builder window with its
model tree and the associated
toolbar buttons gives you an
overview of the model. The
modeling process can be
controlled from
context-sensitive menus
SETTINGS WINDOW — Click
any node in the model tree to
see its associated Settings
window displayed next to the
Model Builder.
GRAPHICS WINDOW TOOLBAR
GRAPHICS WINDOW — The Graphics window presents
interactive graphics for the Geometry, Mesh, and Results
nodes. Operations include rotating, panning, zooming, and
selecting.
INFORMATION W1NDOWS — The Information windows will display vital
model information during the simulation, such as the solution time, solution
progress, mesh statistics, solver logs, and, when available, results tables.
| 7
The screenshot on the previous pages is what you will see when you first start
modeling in COMSOL Multiphysics using the Model Builder. The COMSOL
Desktop® user interface provides a complete and integrated environment for
physics modeling and simulation as well as application design, providing you with
the tools necessary to build a user-friendly interface for your models. You can
customize the desktop to your own needs. The windows can be resized, moved,
docked, and detached. Any changes you make to the layout will be saved when
you close the session and available again the next time you open COMSOL
Multiphysics. As you build your model, additional windows and widgets will be
added. (See page 24 for an example of a more developed desktop.) Among the
available windows and user interface components are the following:
Quick Access Toolbar
The Quick Access Toolbar gives access to functionality such as Open, Save, Undo,
Redo, Copy, Paste, and Delete. You can customize its content from the Customize
Quick Access Toolbar list (the downward-facing arrow to the right of the toolbar).
Ribbon
The ribbon at the top of the desktop gives access to commands used to complete
most modeling tasks. The ribbon is only available in the Windows® version of the
COMSOL Desktop environment and is replaced by menus and toolbars in the
OS X and Linux® versions. Click the Application Builder button to switch from the
Model Builder to the Application Builder and start building an application based
on your model.
Settings Window
This is the main window for entering all of the specifications of the model,
including the dimensions of the geometry, properties of the materials, boundary
conditions and initial conditions, and any other information that the solver will
8 |